Maintaining the quality of seed potatoes from storage to planting is critical to ensuring a successful growing season. In NAPSO Webinar #3, Dr. Kasia Duellman, Extension Seed Potato Specialist at the University of Idaho, provided an in-depth look at essential practices for storing, shipping, handling, and preparing seed potatoes to optimize field performance.

Her presentation highlighted key factors influencing seed health, physiological age, and disease prevention—essential knowledge for growers looking to maximize yield and quality.

Storing Seed Potatoes for Shipment

“The storage phase is crucial for maintaining seed potato viability,” Dr. Duellman said. “Careful temperature and humidity management can slow physiological aging and disease development before shipment.”

Storage Recommendations:

• Gradual temperature adjustments prevent condensation and disease. Storage temperatures should be lowered at a slow rate of 3-4°F per week. However, if airflow is well managed, a faster cooling rate (3-4°F per day) may be beneficial.
• Optimal storage temperatures should be maintained at 34-39°F to preserve dormancy and prevent premature sprouting.
• Proper ventilation and temperature regulation is essential to prevent condensation, which can lead to soft rot.

“At the time of shipping, the seed should be warmed gradually to reduce temperature shock and minimize bruising,” Dr. Duellman pointed out.

Best Practices for Shipping Seed Potatoes

Once seed potatoes leave storage, proper handling during transit ensures they arrive in optimal condition.

Top Shipping Guidelines:

1. Monitor storage temperatures before removal. Pulp temperatures should be above 45°F to reduce bruising risks. However, this only applies to seed that will be cut and treated soon after deliver.
   When buying and transporting seed long before you intend to plant it, keep it cold and handle with extreme gentleness since cold seed is more susceptible to bruising and other wounds.
2. Minimize impact during loading by avoiding drops greater than six inches, as impact can cause mechanical damage.
3. Ensure proper ventilation during transport to prevent moisture buildup, soft rot, and freezing damage.
4. Use refrigerated trucks for long distances to maintain stable temperatures.
5. Educate drivers on handling procedures to prevent losses due to improper airflow, temperature fluctuations, or rough handling.

“Poor shipping conditions—such as temperature fluctuations, condensation, or lack of ventilation—can lead to severe losses in seed viability and plant vigor,” according to Dr. Duellman.

Receiving & Handling Seed

When seed potatoes arrive at their destination, proper handling determines their potential for strong emergence and yield.

Best Practices Upon Arrival:

• Clean and sanitize storage areas and equipment before storing seed to prevent contamination.
• Avoid facilities where CIPC (Chlorpropham) was used, as residue can negatively affect seed health.
• Minimize bruising, which accelerates physiological aging and increases disease susceptibility.

“Wound healing is essential after receiving seed. This process, lasting one to three weeks, allows cut surfaces to suberize, reducing infection risks,” Dr. Duellman said. “If seed arrives cold (less than 40F), and if you don’t plan on planting for some time, keep it cold, and promote wound healing closer to planting time. Again, ‘art vs. science’”.

Ideal Wound Healing Conditions:

• Temperature: 50-70°F
• Humidity: 85-95%
• Airflow: Continuous oxygen supply
• Time Required:
  • 3 days to stop soft rot
  • 1-2 weeks to prevent Fusarium dry rot
  • 1-3 weeks for complete healing

Proper wound healing prevents excessive moisture loss and reduces the risk of pathogens entering cut surfaces.

Physiological Age: A Critical Factor in Seed Performance

According to Dr. Duellman, the physiological age of seed potatoes plays a major role in field performance.

“Unlike chronological age, which is based on time since harvest, physiological age is affected by environmental stress, temperature fluctuations, and handling practices,” she said.

How Physiological Age Affects Growth:

• Young Seed: Fewer stems per plant, longer tuber bulking period, higher potential yield.
• Middle-Aged Seed: Faster emergence, multiple stems, uniform tuber set, suitable for short-season areas.
• Old Seed: Weak sprouting, small tubers, and low vigor.

Dr. Duellman pointed out that older seed may require earlier planting, wider spacing, and larger seed pieces to compensate for reduced vigor.

Cutting & Treating Seed for Planting

Proper cutting and fungicide treatment are crucial in preparing seed for planting.

Key Cutting Guidelines:

• Pre-warm seed to 45-50°F before cutting.
• Optimal seed piece size should be between 1.5-3 oz to maximize productivity.
• Keep blades sharp and sanitize regularly, as dull or contaminated blades increase the risk of disease and poor wound healing.

According to Dr. Duellman, seed size also depends on variety (some may need the larger size, some may be able to do well on the smaller side) and availability (if seed is in short supply, seed size might need to be on the smaller side, which might not be optimal for a particular variety).

Fungicide Treatments for Disease Protection:

• Fusarium dry rot, Rhizoctonia, and silver scurf are the most common seed-borne diseases.
• Liquid fungicide treatments ensure uniform coverage and safety compared to dust formulations.
• Rotating fungicide modes of action from one year to the next helps prevent resistance buildup.

Fungicide treatments are not always necessary—clean seed, using whole seed, and ideal planting conditions may reduce the need for chemical applications.

“I would always recommend a fungicide seed treatment, unless there is some reason you can’t use one,” Dr Duellman said. “It’s cheap insurance. But they do have their limits, such as most only offer protection for about 3 weeks after planting, and if the soil is excessively cold and wet, if the seed is slow to emerge for whatever reason, or if disease pressure is high, a chemical treatment may still fail.”

“Another point is to be sure to use the right fungicide seed treatment for the predicted problem,” she added.

Final Steps: Planting for Success

“The last phase in seed preparation is ensuring optimal planting conditions to promote strong emergence and disease-free growth,” Dr. Duellman told audience.

Planting Best Practices:

• Match seed temperature to soil temperature to avoid stress and emergence delays.
• Prevent overnight exposure in planters to reduce moisture buildup and disease risks.
• Ensure fast emergence through proper spacing, depth, and variety selection.
• Use fungicide seed treatments when needed, particularly when Fusarium dry rot, Rhizoctonia, late blight or silver scurf are concerns.

By following these guidelines, growers can minimize seed loss, optimize crop establishment, and achieve stronger yields.

Conclusion: A Proactive Approach to Seed Potato Success

Dr. Kasia Duellman’s presentation highlighted the importance of careful seed potato management at every stage. Every decision—from storage and shipping to handling, cutting, and planting—affects crop performance and profitability.

“Proper temperature control, ventilation, and handling minimize bruising, regulate physiological age, and reduce disease risks. Implementing best practices for shipping and receiving seed, promoting wound healing, and applying targeted fungicide treatments ensures that growers set their crops up for success,” she said.

Key Takeaways

1. Storage and handling impact seed viability and physiological age.
2. Proper shipping conditions prevent mechanical damage and disease.
3. Understanding physiological age helps optimize planting strategies.
4. Accurate cutting and fungicide treatments improve emergence and disease resistance.
5. Matching planting conditions to seed readiness ensures better field performance.

“With the right management strategies, growers can improve seed performance, protect their investment, and enhance profitability. As environmental and disease pressures evolve, staying informed and proactive is more important than ever,” according to Dr. Duellman.

By applying these practices, growers can ensure every seed counts—leading to healthier plants, stronger yields, and a more resilient potato industry.

For those who missed the webinar, a recording and a pdf file of the presentation are available on the NAPSO website. As part of its ongoing mission, NAPSO continues to offer expert insights, best practices, and industry updates.

Visit NAPSO for more information on storage, handling, and upcoming webinars.

Source: North America Storage Organization (NAPSO)
Contact for further information:
Dr. Kasia Duellman
kduellman@uidaho.edu
Images: Credit Dr. Kasia Duellman